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copied!<p><strong>Use Ruby2Ruby</strong></p> <pre><code>def save_for_later(&block) return nil unless block_given? c = Class.new c.class_eval do define_method :serializable, &block end s = Ruby2Ruby.translate(c, :serializable) s.sub(/^def \S+\(([^\)]*)\)/, 'lambda { |\1|').sub(/end$/, '}') end x = 40 s = save_for_later { |y| x + y } # => "lambda { |y|\n (x + y)\n}" g = eval(s) # => #<Proc:0x4037bb2c@(eval):1> g.call(2) # => 42 </code></pre> <p>This is great, but it does not close over free variables (like <code>x</code>) and serialize them along with the lambda.</p> <p>To <a href="https://stackoverflow.com/questions/503583/how-do-you-access-the-symbol-table-in-ruby">serialize variables</a> also, you can iterate over <code>local_variables</code> and serialize them as well. The problem, though, is that <code>local_variables</code> from within <code>save_for_later</code> accesses only <code>c</code> and <code>s</code> in the code above -- i.e. variables local to the serialization code, not the caller. So unfortunately, we must push the grabbing of local variables and their values to the caller.</p> <p>Maybe this is a good thing, though, because in general, finding all free variables in a piece of Ruby code is <a href="http://en.wikipedia.org/wiki/Undecidable" rel="nofollow noreferrer">undecidable</a>. Plus, ideally we would also save <code>global_variables</code> and any loaded classes and their overridden methods. This seems impractical.</p> <p>Using this simple approach, you get the following:</p> <pre><code>def save_for_later(local_vars, &block) return nil unless block_given? c = Class.new c.class_eval do define_method :serializable, &block end s = Ruby2Ruby.translate(c, :serializable) locals = local_vars.map { |var,val| "#{var} = #{val.inspect}; " }.join s.sub(/^def \S+\(([^\)]*)\)/, 'lambda { |\1| ' + locals).sub(/end$/, '}') end x = 40 s = save_for_later(local_variables.map{ |v| [v,eval(v)] }) { |y| x + y } # => "lambda { |y| _ = 40; x = 40;\n (x + y)\n}" # In a separate run of Ruby, where x is not defined... g = eval("lambda { |y| _ = 40; x = 40;\n (x + y)\n}") # => #<Proc:0xb7cfe9c0@(eval):1> g.call(2) # => 42 # Changing x does not affect it. x = 7 g.call(3) # => 43 </code></pre>

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